Electronic still-video camera, and playback apparatus thereof being capable of storing image data when the storage capacity of a memory card is exceeded

ABSTRACT

An electronic still-video camera is provided capable of preserving image data having a quantity which is greater than the storage capacity of a memory cartridge (memory card) loaded in the camera. Besides being capable of receiving an external memory in a memory cartridge loaded in the camera, the camera incorporates an internal memory. Image data obtained as a result of photography is stored in either the internal memory or the external memory, depending upon which memory has been selected by a memory selection switch.

This application is a continuation of application Ser. No. 07/751,327filed on Aug. 28, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a digital electronic still-video camera forimaging a subject, converting the video signal thus obtained intodigital image data and recording the image data in a memory cartridgecapable of being loaded and ejected at will, and to a playback apparatusfor playing back and displaying the image data resulting from theimaging operation of the digital electronic still-video camera. Thememory cartridge mentioned here has the shape of a case or cardincorporating a semiconductor memory. The term is intended to covermeans such as a memory card.

2. Description of the Related Art

A camera of the kind described in the specification of Japanese PatentPublication (KOKOKU) No. 62-21310 is a known example of a recentelectronic still-video camera. This known electronic still-video camerais adapted to convert a video signal representing the image of a subjectinto a digital quantity and to store the digital quantity as image datain an internal memory incorporated in the body of tile camera. Atplayback, the image data is read out of the internal memory and sent toa playback apparatus via a connector. The playback apparatus convertsthe provided image data into a video signal and applies the video signalto a display unit. As a result, a still picture is displayed on thedisplay unit.

In another example of an electronic still-video camera described in thespecification of Japanese Patent Application Laid-Open (KOKAI) No.59-183582, the image data is recorded in a memory cartridge capable ofbeing loaded in and ejected from the camera body at will.

The first example of the electronic still-video camera mentioned aboveis convenient because it is unnecessary for the user to carry about aseparate memory cartridge. However, the number of frames capable ofbeing photographed is limited by the storage capacity of the internalmemory of the camera, and it is not possible to perform photographybeyond the number of frames decided by the storage capacity of theinternal memory. Using an internal memory having a large storagecapacity permits more photography but raises the cost of the camera. Inaddition, there is a limit also upon the storage capacity of theinternal memory, and therefore in practical use there is no assurancethat the internal memory will always have the capacity to preserve allof the frames desired to be shot.

In the second example of the electronic still-video camera describedabove, an advantage is that preparing the necessary number of memorycartridges makes it possible to perform photography without anylimitation being imposed on the number of frames that can be shot.However, the user must carry about a memory cartridge even if the numberof frames planned on being shot is small. Furthermore, after a memorycartridge has been filled to capacity with the image data, photographycannot be performed unless the memory cartridge is exchanged for a newone.

Further, with the first example of the electronic still-video camera, aseparate playback apparatus is necessary in order to read and reproducethe image data from the internal memory of the camera. Likewise, thesecond example of the electronic still-video camera requires a separateplayback apparatus in order to read and reproduce the image dataobtained by the camera and stored in the memory cartridge.

A disadvantage encountered above is that the playback apparatus for thefirst example of the electronic still-video camera and the playbackapparatus for the second example of the electronic still-video camerahave connectors of different types, and therefore the cameras cannotshare the same playback apparatus. Accordingly, in a case where twotypes of electronic still-video cameras are used for photography, twotypes of playback apparatus also are required. This is inconvenient anddisadvantageous in terms of handling and storage space. In addition, thefact that two types of playback apparatus must be purchased is costlyand is a serious drawback economically speaking.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide aneasy-to-carry electronic still-video camera capable of performingphotography without any limitation upon the number of frames.

Another object of the present invention is to provide an electronicstill-video camera in which, even if the number of recordable framesleft in a memory cartridge has become zero, at least one more frame canbe shot without replacing the memory cartridge.

A further object of the present invention is to provide a playbackapparatus capable of being used to reproduce image data stored in boththe internal memory and external memory (a memory cartridge) of anelectronic still-video camera.

An electronic still-video camera according to a first aspect of thepresent invention comprises image pick-up means for picking up an imageof a subject and outputting a video signal representing the image of thesubject obtained, recording signal processing means for converting thevideo signal outputted by the image pick-up means into digital imagedata suited for storage in a memory, an internal memory for storing theimage data, a first connector in and from which a memory cartridge iscapable of being loaded and unloaded at will, the memory cartridgeincorporating an external memory for storing the image data, and writecontrol means for writing the image data, which has been outputted bythe recording signal processing means, in either the internal memory orthe external memory.

In an embodiment of the invention, the image data is written first inthe internal memory until the internal memory is filled to capacity, andthen in the external memory, by the write control means.

In another embodiment of the invention, the electronic still-videocamera further comprises memory selecting means for selecting either theinternal memory or the external memory. The image data is written in thememory selected by the memory selecting means.

The electronic still-video camera also comprises means for displayingthe number of recordable frames left in the internal memory or theexternal memory, and means for displaying the number of frames of imagedata stored in the internal memory or external memory.

In a preferred embodiment, the electronic still-video camera accordingto the first aspect of the present invention further comprises readcontrol means for reading out the image data stored in the internalmemory or the external memory, playback processing means for convertingthe image data read out by the read control means into a video signalsuited for display, and outputting this video signal, and a secondconnector, to which an external display unit is capable of beingconnected, for supplying the display unit with the video signaloutputted by the playback processing means.

In another preferred embodiment, the electronic still-video cameraaccording to the first aspect of the present invention additionalcomprises read control means for reading out the image data stored inthe internal memory or the external memory, and a third connector, towhich an external playback apparatus is capable of being connected, forsupplying the playback apparatus with the image data read out by theread control means.

An electronic still-video camera according to a first aspect of thepresent invention comprises an internal memory for storing image data, afirst connector, in and from which a memory cartridge is capable ofbeing loaded and unloaded at will, the memory cartridge incorporating anexternal memory for storing the image data, read control means forreading out the image data stored in the internal memory or the externalmemory, playback processing means for converting the image data read outby the read control means into a video signal suited for display, andoutputting this video signal, and a second connector, to which anexternal display unit is capable of being connected, for supplying thedisplay unit with the video signal outputted by the playback processingmeans.

In another embodiment of the invention, the electronic still-videocamera further comprises memory selecting means for selecting either theinternal memory or the external memory. The image data is read out ofthe memory selected by the memory selecting means.

The electronic still-video camera also comprises means for designating aframe number of the image data to be read out of the memory.

The electronic still-video camera additionally comprises a thirdconnector, to which an external playback apparatus is capable of beingconnected, for supplying the playback apparatus with the image data readout by the read control means.

An electronic still-video camera according to a first aspect of thepresent invention comprises an internal memory for storing image data, afirst connector, in and from which a memory cartridge is capable ofbeing loaded and unloaded at will, the memory cartridge incorporating anexternal memory for storing the image data, read control means forreading out the image data stored in the internal memory or the externalmemory, and a second connector, to which an external playback apparatusis capable of being connected, for supplying the playback apparatus withthe image data read by the read control means.

In a preferred embodiment, the electronic still-video camera furthercomprises memory selecting means for selecting either the internalmemory or the external memory. The image data is read out of the memoryselected by the memory selecting means.

The electronic still-video camera further comprises means fordesignating a frame number of the image data to be read out of thememory.

The electronic still-video camera also comprises playback processingmeans for converting the image data read out by the read control meansinto a video signal suited for display, and outputting this videosignal, and a third connector, to which an external display unit iscapable of being connected, for supplying the display unit with thevideo signal outputted by the playback processing means.

In accordance with the first aspect of the present invention, a memorycartridge incorporating an external memory is loaded in the camera,thereby making it possible to shoot a number of frames beyond thestorage capacity (the number of photographable frames) of the internalmemory. In a case where the volume of image data for the required numberof photographic frames is less than the capacity of the internal memory,it is unnecessary for the user to bring along a memory cartridge.Accordingly, the electronic still-video camera is highly portable. Inaddition, since it is unnecessary to rely solely upon the internalmemory in order to shoot all of the desired number of photographicframes, it is possible to hold down the price of the camera. Atplayback, image data stored not only in the internal memory but also inthe external memory can be played back by the playback processing meansand reproduced on the display screen of the display unit. Of course, itis possible also to read the image data out of the external memory orinternal memory and send this image data to the external playbackapparatus.

A playback apparatus for an electronic still-video camera according to asecond aspect of the present invention comprises a first connectorcapable of being connected to the electronic still-video camera foraccepting image data outputted upon being read out of a memory of theelectronic still-video camera, a second connector capable of beingconnected to a memory cartridge for accepting image data outputted uponbeing read out of a memory within the memory cartridge, playback meansfor converting the image data, with which it has been provided, into avideo signal suited for display, and connector selecting means forselecting either the first connector or the second connector andproviding the playback means with the image data supplied through theconnector selected.

In a preferred embodiment, the playback apparatus further comprises athird connector for connecting a display unit provided with the videosignal outputted by the playback means.

The playback apparatus also comprises image designating means fordesignating image data to be read out of the memory of the electronicstill-video camera or the memory of the memory cartridge.

The electronic still-video camera comprises an internal memory forstoring the image data, a connector for connecting a memory cartridgewhich incorporates an external memory for storing the image data, memoryselecting means for selecting read-out of the image data from theinternal memory or the external memory, and image data reading means forreading and outputting designated image data from the memory selected bythe memory selecting means.

The playback apparatus further comprises means for commanding read-outof image data from the internal memory or the external memory of theelectronic still-video camera.

In a preferred embodiment according to the second aspect of the presentinvention, the playback apparatus has a first control panel whichincludes the connector selecting means, and the electronic still-videocamera has a second control panel for commanding operation of thecamera. The playback apparatus further comprises operation selectingmeans for enabling an operating input from one of the first and secondcontrol panels and disabling an operating input from the other of thefirst and second control panels, and causing the playback apparatus toperform an operation, which has been commanded by an operating input, inresponse to the operating input from the enabled control panel.

In another embodiment according to the second aspect of the invention,the playback apparatus further comprises a fourth connector forreceiving an input of an externally applied video signal, and recordingmeans for converting the video signal inputted from the fourth connectorinto image data, and storing the image data in the electronicstill-video camera or the memory of the memory cartridge via the firstor second connector.

In accordance with the second aspect of the present invention, theelectronic still-video camera is connected to the first connector, thememory cartridge is connected to the second connector, and the first orsecond connector is connected to the playback means by the connectorselecting means. As a result, the image data read out via the connectorcan be played back and displayed on the display unit. Accordingly, theimage data recorded in the electronic still-video camera and in thememory cartridge can be played back using a single playback apparatus.

In accordance with the embodiment of the second aspect of the invention,memory selection and playback can be controlled by the user using thefirst control panel of the playback apparatus or the second controlpanel of the electronic still-video camera.

In accordance with the other embodiment of the second aspect of theinvention, a video signal from a VTR or the like inputted from thefourth connector is converted into image data, and the image data can bestored in the electronic still-video camera or the memory cartridge viathe first or second connector. This makes it possible to reproduce therecorded contents of a video tape of the like.

An electronic still-video camera according to a third aspect of thepresent invention comprises image pick-up means for picking up an imageof a subject and outputting a video signal representing the image of thesubject obtained, recording signal processing means for converting thevideo signal outputted by the image pickup means into digital image datasuited for storage in a memory, and for compressing the digital imagedata, an internal memory for storing the compressed image data, a firstconnector in and from which a memory cartridge is capable of beingloaded and unloaded at will, the memory cartridge incorporating anexternal memory for storing the compressed image data, and write controlmeans for writing the compressed image data, which has been outputted bythe recording signal processing means, in either the internal memory orthe external memory.

In an embodiment according to the third aspect of the present invention,the electronic still-video camera further comprises memory selectingmeans for selecting either the internal memory or the external memory.The compressed image data is written in the memory selected by thememory selecting means.

It is particularly preferred that the electronic still-video camera alsocomprises means for displaying the number of recordable frames left inthe internal memory or the external memory, and means for displaying thenumber of frames of image data stored in the internal memory or externalmemory.

In another embodiment, the electronic still-video camera comprises readcontrol means for reading out the compressed image data stored in theinternal memory or the external memory, and playback processing meansfor expanding the compressed image data read out by the read controlmeans, converting the expanded image data into a video signal suited fordisplay, and outputting this video signal.

The electronic still-video camera further comprises a second connector,to which an external display unit is capable of being connected, forsupplying the display unit with the video signal outputted by theplayback processing means.

The electronic still-video camera also comprises a display unit fordisplaying an image represented by the video signal outputted by theplayback processing means.

In another embodiment of the present invention, the electronicstill-video camera additionally comprises means for transferring thecompressed image data from the internal memory to the external memory,or vice versa.

The electronic still-video camera further comprises means fordesignating the compressed image data to be transferred.

The transfer means may be adapted to transfer all of the compressedimage data stored in the internal memory or external memory.

An electronic still-video camera according to a third aspect of thepresent invention comprises an internal memory for storing compressedimage data, a first connector in and from which a memory cartridge iscapable of being loaded and unloaded at will, the memory cartridgeincorporating an external memory for storing the image data, readcontrol means for reading out the compressed image data stored in theinternal memory or the external memory, and playback processing meansfor expanding the compressed image data read out by the read controlmeans, converting the expanded image data into a video signal suited fordisplay, and outputting this video signal.

In a preferred embodiment, the electronic still-video camera furthercomprises memory selecting means for selecting either the internalmemory or the external memory. The compressed image data is read out ofthe memory selected by the memory selecting means.

In an embodiment according to the third aspect of the present invention,the electronic still-video camera also comprises a second connector, towhich an external display unit is capable of being connected, forsupplying the display unit with the video signal outputted by theplayback processing means.

According to another embodiment, the electronic still-video cameraadditionally comprises a display unit for displaying an imagerepresented by the video signal outputted by the playback processingmeans.

An electronic still-video camera according to a third aspect of thepresent invention comprises image pick-up means for picking up an imageof a subject and outputting a video signal representing the image of thesubject obtained, recording signal processing means for converting thevideo signal outputted by the image pick-up means into digital imagedata suited for storage in a memory, and for compressing the digitalimage data, an internal memory for storing the compressed image data, aconnector in and from which a memory cartridge is capable of beingloaded and unloaded at will, the memory cartridge incorporating anexternal memory for storing the compressed image data, write controlmeans for writing the compressed image data outputted by the recordingsignal processing means in either the internal memory or externalmemory, and means for transferring the compressed image data from theinternal memory to the external memory or vice versa.

In a preferred embodiment, the electronic still-video camera furthercomprises means for designating the compressed image data to betransferred.

The transfer means may be adapted to transfer all of the compressedimage data stored in the internal memory or external memory.

accordance with the third aspect of the present invention, photographyis possible without carrying about a memory cartridge, just as in thefirst aspect of tile present invention. The data representing theacquired image is capable of being stored in the internal memory. Theimage data that has been stored in the internal memory can betransferred to the external memory of the memory cartridge and thereforeis capable of being preserved in the external memory. Naturally, in acase where the number of photographs is large, the memory cartridge isloaded so that the photographic image data can be preserved in thememory cartridge. Since the image data is subjected to compressionprocessing, memory capacity can be utilized very effectively.

An electronic still-video camera according to a fourth aspect of thepresent invention comprises image pick-up means for picking up an imageof a subject and outputting a video signal representing the image of thesubject obtained, recording signal processing means having a framememory for converting the video signal outputted by the image pick-upmeans into digital image data suited for storage in a memory, and forcompressing the digital image data, a connector in and from which amemory cartridge is capable of being loaded and unloaded at will, thememory cartridge incorporating an external memory for storing thecompressed image data, sensing means for sensing that the memorycartridge has been connected to the connector, determining means fordetermining that compressed image data can no longer be recorded in thememory cartridge connected to the connector, and control means, when ithas been determined by the determining means that the compressed imagedata can no longer be recorded in the memory cartridge after the digitalimage data, which has been obtained by image pick-up performed by theimage pick-up means and results from the conversion performed by therecording signal processing means, and has been stored in the framememory, operable for performing control in such a manner that the imagedata stored in the frame memory is written in a new memory cartridgeonce it has been confirmed based upon information from the sensing meansthat the memory cartridge has been replaced by the new memory cartridge.

In an embodiment according to the fourth aspect of the presentinvention, the recording signal processing means includes a Y/Cprocessing circuit for generating luminance data and color data from thedigital image data, and a compressing circuit for compressing the imagedata after it has been subjected to Y/C processing. Once the image datasubjected to Y/C processing has been preserved in the frame memory andreplacement of the memory cartridge has been confirmed, the image datais compressed and then recorded in the new memory cartridge.

In another embodiment, the electronic still-video camera furthercomprises means for displaying a memory-cartridge replacement requestwhen it has been determined by the determining means that compressedimage data is no longer capable of being recorded in the memorycartridge.

In a preferred embodiment, the electronic still-video camera alsocomprises means for cancelling automatic turn-off of power when amemory-cartridge replacement request has been displayed by the displaymeans.

An electronic still-video camera according to a fourth aspect of thepresent invention comprises image pick-up means for picking up an imageof a subject and outputting a video signal representing the image of thesubject obtained, recording signal processing means having a framememory for converting the video signal outputted by the image pick-upmeans into digital image data suited for storage in a memory, and forcompressing the digital image data, a connector in and from which amemory cartridge is capable of being loaded and unloaded at will, thememory cartridge incorporating an external memory for storing thecompressed image data, sensing means for sensing that the memorycartridge has been connected to the connector, and control means which,when it has been sensed by the sensing means that the memory cartridgehas not been connected to the connector after the digital image dataobtained by image pick-up performed by the image pick-up means andresulting from conversion performed by the recording signal processingmeans has been stored in the frame memory, which is operable forperforming control in such a manner that the image data stored in theframe memory is written in a memory cartridge once it has been confirmedby the sensing means that the memory cartridge has been connected to theconnector.

In accordance with the fourth aspect of the present invention, a framememory essential for digital signal processing within the digitalelectronic still-video camera is utilized. As a result, if it is desiredto perform photography beyond an already fixed number of photographicframes of the memory cartridge, at least one frame can be preservedtemporarily irrespective of the size of the compression ratio. Inaddition, even if memory cartridge has not been loaded in the camera,image data resulting from photography can be preserved in the framememory temporarily. By operating the camera in such a manner that thetemporarily preserved image data is recorded in a new memory cartridgewhen the new memory cartridge has been loaded in the camera, theoperator's task is simplified greatly.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the electronic circuitry of anelectronic still-video camera according to a first embodiment of thepresent invention;

FIG. 2 is an external perspective view of the electronic still-videocamera;

FIGS. 3a through 3c are diagrams illustrating examples of displays whichappear on a liquid-crystal display device of the electronic still-videocamera;

FIG. 4 is a block diagram illustrating the electronic circuitryincorporated within a playback apparatus for an electronic still-videocamera according to a second embodiment of the present invention;

FIG. 5 is an external perspective view of the electronic still-videocamera and playback apparatus;

FIG. 6 is a block diagram illustrating the electronic circuitry of theplayback apparatus according to a modification of the present invention;

FIG. 7 is a block diagram illustrating the electrical construction of adigital electronic still-video camera according to a third embodiment ofthe present invention;

FIG. 8 is a diagram illustrating a display panel of the digitalelectronic still-video camera;

FIG. 9 is a diagram illustrating a control panel of the digitalelectronic still-video camera;

FIG. 10 is a block diagram illustrating the electrical construction of adigital electronic still-video camera according to a fourth embodimentof the present invention;

FIG. 11 is a flowchart illustrating the operation of the digitalelectronic still-video camera; and

FIG. 12 is a diagram showing various areas of an external memory thatare contained in a memory card.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described in detailwith reference to the drawings.

First Embodiment

An electronic still-video camera 10 according to a first embodiment ofthe present invention has a photographic lens 8 and a finder lens 9provided on its front side, as illustrated in FIG. 2. A shutter-releasebutton 11 and a liquid-crystal display device 12 are provided on the topside of the electronic still-video camera 10. The display panel of theliquid-crystal display device 12 is divided into three display sections12A, 12B and 12C. Disposed alongside the liquid-crystal display device12 is a control panel (indicated by numeral 20 in FIG. 1) which includesa memory selecting switch 13, a main switch 14, a forward button 16, areverse button 17 and an erase button 18. An accommodating recess for aconnector 19 which connects an external playback apparatus 32 (seeFIG. 1) is open and shut by sliding a cover 21.

When the memory selecting switch 13 is set at the position of anindicator mark 22, an internal RAM 28 incorporated within the camera 10is selected, as shown in FIG. 1. When the memory selecting switch 13 isset at the position of an indicator mark 23, an external RAM 31 within amemory cartridge 29 is selected. Thus, it is possible for image data tobe stored in or read out of the selected RAM. In this embodiment, theRAMs 28 and 31 each have a storage capacity of 12 photographic frames.

When the main switch 14 is set at the position of an indicator mark 25,the main electronic circuitry within the camera 10 ceases operating, andoperating power is supplied solely to the minimum required circuitry,such as a circuit needed to maintain the data stored in the internal RAM28. This makes it possible to minimize power consumption. When the mainswitch 14 is changed over to the position of an indicator mark 26, thisestablishes an image playback mode. Changing over the main switch 14 tothe position of an indicator mark 27 establishes an image recordingmode.

One side of the electronic still-video camera 10 has an opening 33 intowhich the memory cartridge 29 is inserted. Provided within the interiorof the opening 33 is a connector 34 for connecting the memory cartridge29. A connector 37 for connecting an external monitor (see FIG. 1) forimage playback is provided alongside the opening 33.

When the shutter-release button 11 is pressed, a timing generator 40shown in FIG. 1 generates a clock pulse. In response to the clock pulse,a CCD 38 outputs a video signal representing the image of a subjectphotographed. The video signal is converted into digital data by an A/Dconverter 39, and the digital data is supplied to a signal processingcircuit 41. The signal processing circuit 41 separates color informationand luminance information of each pixel from the video signal andproduces image data by combining these items of information with addressinformation of each pixel generated based upon the clock pulse and a dotclock signal. The image data is directed through an interface 42 to bestored in the internal RAM 28 or the external RAM 31, depending upon thesetting of the memory selecting switch 13.

The states of the various buttons and switches on the control panel 20are constantly being monitored by a CPU 44. If the shutter-releasebutton 11 is pressed when the indicator mark 27 has been selected by themain switch 14, one frame of image data resulting from photography istransferred from the interface 42 to either the internal RAM 28 or theexternal RAM 31. When the indicator mark 25 or 26 has been selected bythe main switch 14, depression of the shutter-release button 11 isconsidered an invalid operation and no clock pulse is generated by thetiming generator 40.

A cartridge detector circuit 46 connected to the connector 34 detectsloading of the memory cartridge 29 and sends a signal indicative thereofto the CPU 44. The latter reads the header information of the storagearea of the external RAM 31 in the memory cartridge 29 via the interface42 and, based upon the header information, recognizes the number ofphotographable frames left in the external RAM 31 of the memorycartridge 29 and the number of already photographed frames stored in theexternal RAM 31. Power necessary for backing up the external RAM 31 issupplied by a battery in a power-supply circuit 48 incorporated in thememory cartridge 29.

FIG. 3a illustrates examples of displays presented on the liquid-crystaldisplay device 12 when the memory cartridge 29 has not been loaded. Inexamples 53, 54 and 55, the number "12" of photographable framesconforming to the storage capacity of the internal RAM 28 is displayedin the display section 12A. In examples 54 and 55, the number ofphotographed frames already stored in the internal RAM 28 is displayedin display section 12B. The number of photographed frames is incrementedfrom "0" to "1", "1" to "2" and so on, up to "12", each time a frame isshot.

When the memory cartridge 29 has been loaded, the display on theliquid-crystal display device 12 changes over, as shown in FIG. 3b.

In display example 57, the indication "CA 12" in the display section 12Aindicates that the number of photographable frames in memory cartridge29 is 12. The underlying numeral "0" indicates that the number of shotframes already stored in the memory cartridge 29 is 0.

The indication "IN 12" which appears in the display section 12Bindicates that the number of photographable frames in the internal RAM28 is 12. The underlying numeral "0" indicates that the number of shotframes already stored in the internal RAM 28 is 0. The mark " " to theleft of "0" means that if the shutter-release button 11 is pressed underthese conditions, the first frame of image data representing the imageof the photographed subject will be recorded in the internal RAM 28. Ifphotography continues in this manner, the display will change as shownin display examples 58 and 59 in FIG. 3b.

If the memory selecting switch 13 is changed over to the position ofindicator mark 23 when the display of example 57 is in effect, the mark" " moves to the display section 12A, as depicted in display example 61of FIG. 3c. The display example 61 indicates that if photography isperformed by pressing the shutter-release button 11, the first frame ofimage data resulting from photography will be stored in the external RAM31 within the memory cartridge 29. If photography continues, the numberof shot frames changes from the display example 61 to display example 63via display example 62. When the number of shot frames recorded in theexternal RAM 31 reaches the number 12 of photographable frames, the mark" " moves to the display section 12B (display example 63) correspondingto the internal RAM 28 (which still has storage capacity available),even if the memory selecting switch 13 is not changed over. If thememory selecting switch 13 is changed over to the position of indicatormark 22 in mid course, the image data resulting from photography can bestored in the internal RAM 28 so that some storage capacity is left inthe external RAM 31, as illustrated in display example 64.

Each frame of image data stored in the RAM 28 or 31 has a frame numberassigned thereto by the CPU 44 in accordance with the order in whichpictures are taken. The display section 12C displays informationindicating, for example, that the battery within the power-supplycircuit 47 is running low on energy.

The display on the liquid-crystal display device 12 associated with theoperation of the memory selecting switch 13 is presented in a similarmanner in the image playback mode as well. In the playback mode, thenumerals underlying "CA 12" or "IN 12" indicate the frame number, in theexternal RAM 31 or the internal RAM 28, of the image currently beingdisplayed on a monitor display unit 36 or 51. Depending upon whether themark " " is being displayed in the display section 12A or 12B, the markindicates that the image currently being displayed on the displaymonitor has been read out of the internal RAM 28 or the external RAM 31.

Each time the forward button 16 is pressed, the frame number isincremented and the image data of this frame number is read out of theinternal RAM 28 or the external RAM 31 and displayed on the monitor.When the reverse button 17 is pressed, the frame number is decrementedin successive fashion. If the forward button 16 or the reverse button 17is pressed and held, frames of image data are displayed on the monitorone after another rapidly in the forward or reverse direction,respectively.

If the shutter-release button 11 is pressed while the erase button 18 isheld depressed in the playback mode, the image data of the framecurrently appearing on the monitor is erased from the internal RAM 28 orthe external RAM 31.

When the main switch 14 is set at the position of indicator mark 26, theimage playback mode is established, as described above, the image datain the internal RAM 28 or the external RAM 31 is read out via theinterface 42, and the read image data is sent to a playback circuit 49and the connector 19. The playback circuit 49 converts the digital imagedata read out of the internal RAM 28 or the external RAM 31 into analogimage data and produces a composite video signal which includeshorizontal and vertical synchronizing signals formed from addressinformation. This video signal is applied to the external monitordisplay unit 36 connected to the connector 37. As a result, a reproducedimage represented by the video signal appears on the display unit 36.The external playback apparatus 32 connected to connector 19, besidesexecuting processing similar to that of the playback circuit 49, iscapable of executing processing for changing the color tone of the imageappearing on the monitor display unit 51 or for converting a color imageto a black-and-white image.

The operation of the first embodiment will now be described.

in a case where the user expects that the number of frames to be shotwill be 12 or less, the user needs to carry only the electronicstill-video camera 10 and is not required to take along the memorycartridge 29.

When a picture is to be taken, first the main switch 14 is changed overfrom the position of indicator mark 25 to the position of indicator mark27. As a result, "12" is displayed in the display section 12A and "0" inthe display section 12B of the liquid-crystal display device 12, asillustrated by display example 53 in FIG. 3a. This indicates that thenumber of photographable frames in the internal RAM 28 is 12 and thatthe number of shot frames is 0. When the shutter-release button 11 ispressed to shoot the first frame, the image data of Frame No. 1 isstored in the internal RAM 28 and the numeral in the display section 12Bchanges to "1". The numeral appearing in the display section 12B isincremented whenever the shutter-release button 11 is pressed. When thisnumber attains the number "12" appearing in the display section 12A, thenumber of photographable frames and the number of already shot frames inthe internal RAM 28 coincide. This means that no further photography ispossible. When photography ends, the main switch 14 is changed over tothe position of indicator mark 25 to prevent consumption of the powersupply.

When the main switch 14 is changed over to the position of the indicatormark 26, the circuit is placed in the playback mode and the displaypresented on the liquid-crystal display device 12 takes on the form ofdisplay example 53 in FIG. 3a. When the monitor display unit 36 isconnected to the connector 37, the screen of the display unit 36 goesblank. When the forward button 16 is pressed one time, the displaysection 12B displays "1" and the monitor display unit 36 displays theimage of Frame No. 1 among the twelve frames that have been shot. Bysubsequently pressing the forward button 16 or reverse button 17, imageshaving different frame numbers are displayed on the monitor display unit36 one after another and the frame numbers of the respective images aredisplayed in the display section 12B. If the frame number of the imagedesired to be displayed is known, the forward button 16 or reversebutton 17 is pressed to display the frame number in the display section12B, thereby making it possible to retrieve the desired image basedsolely upon the frame number. By connecting the playback apparatus 32 tothe connector 19, the image having the same frame number as thatdisplayed on the monitor display unit 36 can be displayed in a differentform on the other monitor display unit 51.

If the number of frames to be shot is expected to be large or is notknown, the required number of memory cartridges is carried along withthe electronic still-video camera 10. To perform photography, the mainswitch 14 is changed over from the position of indicator mark 25 to thatof indicator mark 27 to establish the image recording mode. At this timea display of the kind illustrated by display example 53 appears on theliquid-crystal display device 12.

When the memory cartridge 29 is loaded from the opening 33 and connectedto the connector 34, the cartridge detector circuit 46 outputs adetection signal. By setting the memory selecting switch 13 to theposition of indicator mark 22, the display presented by theliquid-crystal display device 12 changes to the display example 57 ofFIG. 3b.

When the shutter-release button 11 is pressed, the first frame of imagedata resulting from photography is stored in the internal RAM 28, andthe numeral underlying "IN 12" in display section 12B changes to "1"(display example 58). If photography is continued, the numeralunderlying "IN 12" is incremented. When shooting of the 12th frame ends,the numeral underlying "IN 12" becomes "12", which is equal to thenumber of photographable frames in the internal RAM 28. At this time,the mark " " moves to the display section 12A, as shown in displayexample 59, and image data resulting from photography from the 13thframe onward is recorded in the external RAM 31 in memory cartridge 29.

If the memory cartridge 29 has been loaded and the memory selectingswitch 13 is changed over from the position of indicator mark 22 to thatof indicator mark 23, the mark " " moves from the display section 12B tothe display section 12A, as illustrated by display example 61 in FIG.3c. Each time the shutter-release button 11 is pressed under theseconditions, each frame of image data is stored in the external RAM 31and the numeral underlying "CA 12" is incremented. When shooting of the12th frame ends, the number of shot frames reaches the number ofphotographable frames in the external RAM 31. Accordingly, the mark " "moves from the display section 12A to the display section 12B and framesshot from the 13th onward are recorded in the internal RAM 28.

If the user does not wish to record image data in the internal RAM 28,the memory cartridge 29 is replaced by an unused one, thereby allowingphotography to resume while leaving the internal RAM 28 unused. Theimage data resulting from the resumed photography can thus be stored inthe newly loaded memory cartridge 29. When the new memory cartridge 29is loaded, the display on the liquid-crystal display device 12 becomesas illustrated by display example 61 in FIG. 3c.

If photography is resumed with the memory selecting switch 13 left setat the position of indicator mark 23 and the memory selecting switch 13is then changed over to the position of indicator mark 22 when the fifthframe is shot, for example, the display on the liquid-crystal displaydevice 12 becomes as illustrated by display example 64. By subsequentlypressing the shutter-release button 11, the sixth frame of image datacan be recorded in the internal RAM 28 as image data of Frame No. 1.

If the memory cartridge 29 has been loaded, the main switch 14 is set atthe position of indicator mark 26 and the memory selecting switch 13 isset at the position of the indicator mark 22, the liquid-crystal displaydevice 12 presents the display illustrated by display example 57. Indisplay example 57, the mark " " resides in the display section 12B,thereby indicating that the playback of data performed from this pointonward will be image data stored in the internal RAM 28. By pressing theforward button 16, the image represented by the image data of Frame No.1 stored in the internal RAM 28 is displayed. The image displayed on themonitor display unit 36 can be selected by subsequently operating theforward button 16 or reverse button 17.

If the external RAM 31 is selected by changing over the memory selectingswitch 13, the mark " " moves to the display section 12A and the imagesthat have been recorded in the external RAM 31 can be played back.

In a case where only one frame of image data no longer needed is erased,the main switch 14 is set at the position of indicator mark 26 toestablish the playback mode and the image of the frame to be erased isdisplayed on the monitor by operating the forward button 16 or reversebutton 17. If the shutter-release button 11 is pressed while holdingdown the erase button 18 under these conditions, this frame of imagedata is erased and the image data corresponding to this frame number iscleared from the RAM. Accordingly, the next time a picture is taken, newimage data can be recorded at the recording position having this framenumber.

If the frame number of the image to be erased is evident, this framenumber can be selected and its corresponding image erased whileobserving the display on the liquid-crystal display device 12, withoutpresenting a display on the monitor.

In the embodiment described above, the arrangement is such that the RAMwhich records the image data can be selected by the memory selectingswitch 14. However, it is permissible to adopt an arrangement in whichthe first through 12th frames of image data are always recorded in theinternal RAM 28 and images from the 13th frame onward, which exceeds thenumber of photographable frames in the internal RAM 28, are recorded inthe external RAM 31 of the memory cartridge 29. As a result, an objectof the present invention is attained by a simplified operation.

As will be illustrated by a third embodiment set forth below, it can beso arranged that a selector and a command switch for copy or transferare provided, and the image data that has been stored in the internalRAM 28 is directed through the selector and transferred for storage tothe external RAM 31 of the memory cartridge 29 when a copy or transfercommand is issued by the command switch. It is possible also to performtransfer and storage in the opposite direction, namely from the externalRAM 31 to the internal RAM 28. In this case, it would be desirable if itwere possible to designate the frame number of the image data to betransferred.

Second Embodiment

A playback apparatus 110 for an electronic still-video camera accordingto a second embodiment of the present invention has an opening 113provided in its front side for inserting and ejecting a memory cartridge112. The memory cartridge 112 incorporates an external RAM 114 forstoring image data. Connectors 116 and 117 are disposed on the rightside of the opening 113. The connector 116 is an image-data inputterminal for use in the playback mode, and the connector 117 is avideo-signal input terminal for use in the recording mode.

The electronic still-video camera 10 is the same as that of the firstembodiment discussed above, and portions identical with those shown inFIGS. 1 and 2 are designated by like reference characters and need notbe described again. The electronic still-video camera 10 is providedwith a connector 37A for input/output of image data. The connector 37Aand connector 116 are connected by a cable 118, thereby interconnectingthe camera 10 and the playback apparatus 110. The memory cartridge 29inserted into and ejected from the electronic still-video camera 10 andthe memory cartridge 112 inserted into and ejected from the playbackapparatus 110 are the same. In other words, the memory cartridge 112 canbe used with the camera 10, and the memory cartridge 29 can be used withthe playback apparatus 110.

If the electronic still-video camera 10 and the playback apparatus 110are connected by the cable 118, the electronic still-video camera 10 isplaced in the recording mode and the shutter-release button 11 ispressed under these conditions, the usual photography is not carriedout. Rather, image data inputted from the playback apparatus 110 isstored in the internal RAM 28 or the external RAM 31 via the cable 118.

The right side of the playback apparatus 110 is provided with aconnector 132 for outputting a video signal. A monitor display unit 135connected to the connector 132 displays an image represented by thevideo signal outputted by the playback apparatus 110.

The top side of the playback apparatus 110 is provided with a controlpanel 139 (see FIG. 4) and a warning lamp 141. The control panel 139includes a main switch 133, a connector selecting switch 134, anoperation selecting switch 136, a forward button 137, a reverse button138 and a recording button 131.

By setting the main switch 133 at the position of an indicator mark 142,143 or 144, as shown in FIG. 4, the electronic circuitry within theplayback apparatus 110 is placed in an off state, playback mode orrecording mode, respectively.

If the connector selecting switch 134 is set at the position of theindicator mark 146, the connector 116 is selected and image data isaccepted via this connector. If the connector selecting switch 134 isset at the position of the indicator mark 147, a connector 148 isselected and image data is accepted via this connector. The memorycartridge 112 that has been loaded in the opening 113 is connected tothe connector 148. A CPU 152 senses whether a connection has been madeto the connector 116 for the electronic still-video camera 10 or theconnector 148 for the memory cartridge 112. If the electronicstill-video camera 10 or memory cartridge 112 has not been connected tothe selected connector 116 or 148, the warning lamp 141 is lit by awarning signal produced by the CPU 152 to inform the user of thesituation.

The operation selecting switch 136 is for enabling operation of thecontrol panel 20 of electronic still-video camera 10 or operation of thecontrol panel 139 of the playback apparatus 110 if the electronicstill-video camera 10 has been connected to the connector 116. If theswitch 136 is at the position of indicator mark 149, operation of thecontrol panel of playback apparatus 110 is enabled and operation of thecontrol panel of electronic still-video camera 10 is disabled. If theswitch 136 is at the position of indicator mark 150, operation of thecontrol panel of electronic still-video camera 10 is enabled andoperation of the control panel 139 of the playback apparatus 110 isdisabled.

More specifically, the CPU 44 of the electronic still-video camera 10and the CPU 152 of the playback apparatus 110 are interconnected via thecable 118. The CPUs 44 and 152 inform each other of the states of theread input signals from the respective control panels 20 and 139.Accordingly, depending upon the setting of the operation selectingswitch 136, it is possible to control the playback apparatus 110 fromthe control panel 20 of the electronic still-video camera 10 and,conversely, it is possible to control the electronic still-video camera10 from the control panel 139 of the playback apparatus 110.

If the forward button 137 is pressed with the main switch 133 set at theposition of the indicator mark 143, image data having a frame numberincremented by one is read out and played back from the image data thathas been stored in the internal RAM 28 of electronic still-video camera10 or in the external RAM 114 of memory cartridge 112. Conversely,pressing the reverse button 138 causes image data having a frame numberdecremented by one to be played back. By holding down the button 137 or138 continuously, images to be played back are fed successively frame byframe in the forward or reverse direction, respectively.

When the electronic still-video camera 10 and memory cartridge 112 areconnected to the connectors 116 and 148, respectively, this condition issensed by the CPU 152. The CPU 152 controls the circuitry in theelectronic still-video camera 10 or memory cartridge 112 via theconnector 116 or 148 to perform read-out of the necessary image data,RAM selection, etc. Image data supplied via the connector 116 or 148 isselected in a selector 153 under the control of the CPU 152, and theselected image data is supplied to the playback circuit 156 via aselector 154.

A pulse generating circuit 166 applies a timing pulse to a recordingcircuit 157 when the recording button 131 is pressed. The timing pulsestipulates the timing at which the recording circuit 157 is to process avideo signal corresponding to one image.

The playback circuit 156 performs a digital-to-analog conversion onvarious information possessed by the image data and produces a compositevideo signal which includes horizontal and vertical synchronizingsignals formed from address information. This video signal is applied tothe monitor display unit 135 via the connector 132. As a result, animage represented by the video signal appears on the screen of thedisplay unit 135.

The recording circuit 157 performs an operation which is the reverse ofthat executed by the playback circuit 156. Specifically, a compositevideo signal acquired from a VTR (video tape recorder) 158 via theconnector 117 is converted from an analog to digital signal in units ofone image and separated into various items of information to produceimage data. This image data is stored in the internal RAM 28 ofelectronic still-video camera 10 or in the external RAM 114 of memorycartridge 112 via the selectors 154 and 153.

When the image playback mode is established by pressing a playbackswitch 158B on the VTR 158 connected to the connector 117, a movingpicture recorded on a video tape 165 is played back and displayed on thescreen of a monitor display unit 164. A video signal representing themoving picture appearing on the display screen is outputted from avideo-signal output terminal 158A of the VTR 158 and supplied to theconnector 117. The moving picture is composed of a number of collectedstill pictures of individual images (scanning time: 1/60 sec). Videosignals representing the individual still pictures are continuouslysupplied to the recording circuit 157 via the connector 117.

Ordinarily, the recording circuit 157 does not process the suppliedvideo signal. When the pulse generating circuit 166 outputs a timingpulse in response to depression of the recording button 131, therecording circuit 157 is placed in a signal-standby state in order tobegin recording processing. In response to attainment of this state anddetection of the vertical synchronizing signal of the video signalinitially supplied, the recording circuit 157 starts video-signalprocessing and then ends this processing in response to detection of thenext vertical synchronizing signal. As a result, only a video signalcorresponding to one image is converted into digital image data. Theoperating states of the control panel 139, such as depression of therecording button 131, are scanned by the CPU 152 at all times.

The VTR 158 is provided with a temporary-stop switch 158C. By pressingthis switch, one desired image stored in a frame memory within the VTR158 can be "frozen" on the monitor screen, and output of the videosignal representing this image can be made to continue in repetitivefashion. By pressing the recording button 131 while an image is frozenon the monitor screen, the data indicative of the frozen image can berecorded and reproduced in the playback apparatus 110 in a reliablemanner.

The operation of the second embodiment constructed as set forth abovewill now be described.

At playback, the connector 37A of the electronic still-video camera 10,in which image data has been stored in the internal RAM 28 and theexternal RAM 31, and the connector 116 of the playback apparatus 110 areconnected by the cable 118. The memory cartridge 112 is loaded from theopening 113 and connected to the connector 148. Furthermore, the monitordisplay unit 135 is connected to the connector 132. The operation of thecontrol panel 139 is enabled by setting the operation selecting switch136 to the position of indicator mark 149. Thereafter, the main switch133 is changed over from the position of indicator mark 142 to that ofthe indicator mark 143, whereby the selector 154 selects the side of theplayback circuit 156. As a result, the electronic circuitry of theplayback apparatus 110 is placed in the playback mode.

If the connector selecting switch 134 has been set at the position ofthe indicator mark 146, the selector 153 selects the side of theconnector 116 and image data outputted by the electronic still-videocamera 10 is accepted. This image data is supplied to the playbackcircuit 156 via the selectors 153,154, whereby the data is convertedinto an analog video signal suitable for display. The monitor displayunit 135, which has been supplied with the video signal via theconnector 132, projects a still picture represented by the video signalon its monitor screen. The frame number of the image being displayed onthe monitor appears on the liquid-crystal display device 12 of theelectronic still-video camera 10.

The image being displayed on the monitor can be selected from theinternal RAM 28 or the external RAM 31 by operating the forward button137 or reverse button 138 while observing the image displayed on themonitor. If the forward button 137 is held depressed, the image of FrameNo. 1 in the internal RAM 28 is displayed on the monitor first, followedby images having successively larger frame numbers. Following the imagehaving the last frame number in the internal RAM 28, the images in theexternal RAM 31 are displayed on the monitor one after another startingfrom Frame No. 1. The images can be displayed on the monitor in theorder of successively smaller frame numbers by pressing the reversebutton 138.

If the connector selecting switch 134 has been set at the position ofthe indicator mark 147, the selector 153 selects the side of the memorycartridge 112. Image data is accepted from the external RAM 114 in thememory cartridge 112. The image represented by the image data that hasbeen recorded in the memory cartridge 112 is displayed on the monitordisplay unit 135, just as described above.

In a case where solely the electronic still-video camera 10 or memorycartridge 112 is connected to connector 116 or 114, image data acceptedfrom the connector which the connection has been made can be played backby selecting this connector by means of the connector selecting switch134. However, when the connector to which the connection has been madeis not selected, the CPU 152 will light the warning lamp 141, in orderto inform the user that playback as selected is impossible, if theconnector selecting switch 134 is set at the position of the indicatormark 146 with the memory cartridge 112 having been connected to theconnector 148 and the electronic still-video camera 10 having not beenconnected to the connector 116, by way of example.

At recording, the video-signal output terminal 158A of the VTR 158 isconnected to the connector 117, and the main switch 133 is set at theposition of the indicator mark 144. As a result, the selector 154selects the side of the recording circuit 157 in response to a commandfrom the CPU 152, and the electronic circuitry of the playback apparatus110 is placed in the recording mode.

The connector 116 or 148 is selected by the connector selecting switch134. The VTR 158 is placed in an image playback state when the playbackswitch 158B is pressed. If the temporary-stop switch 158C is pressedwhile the image playback state is in effect, the image prevailing atthis time is frozen on the screen of the monitor display unit 164. Thevideo signal of the still picture being displayed on the monitor issupplied continuously to the recording circuit 157 via the video-signaloutput terminal 158A and connector 117.

If the recording button 131 is pressed while the video signal of onedesired image is being supplied continuously to the recording circuit157, the pulse generating circuit 166 supplies the recording circuit 157with a timing pulse. The recording circuit 157 which has been suppliedwith the timing pulse begins processing for converting the video signalinto image data in response to detection of the vertical synchronizingsignal. This processing stops in response detection of the next verticalsynchronizing signal. The image data corresponding to one image thusobtained is directed through the selector 154 and supplied to theconnector 116 or 148 selected by the selector 153. This data is storedin the internal RAM 28 (or the external RAM 31) or in the external RAM114. Operation of the warning lamp 141 in the recording mode is similarto that in the playback mode.

In a case where the operation selecting switch 136 has been set at theposition of indicator mark 150, the selector 153 selects the side ofconnector 116. With the exception of the operation selecting switch 136,operation of the control panel 139 is disabled and operation of theelectronic still-video camera 10 is enabled.

When the main switch 14 of the electronic still-video camera 10 is setat the position of indicator mark 26, the CPU 152 responds by causingthe selector 154 to select the playback circuit 156 and places theelectronic circuitry of the playback apparatus 110 in the playback mode.Now, by operating the memory selecting switch 13, either the internalRAM 28 or external RAM 31 is selected, and the frame number is selectedby operating the forward button 16 or the reverse button 17. The imagedata of the frame number thus selected is read out of the internal RAM28 or the external RAM 31, and the image represented by read data isdisplayed on the screen of the monitor display unit 135.

By setting the main switch 14 at the position of the indicator mark 27,the selector 154 selects the side of the recording circuit 157 and theelectronic circuitry of the playback apparatus 110 is placed in therecording mode. If the VTR 158 is operated under these conditions todisplay a desired still picture on the monitor display unit 164, thevideo-signal output terminal 158A will continuously deliver an output ofthe video signal indicative of this still picture. By pressing theshutter-release button 11, the recording circuit 157 is supplied withtiming pulses from the pulse generating circuit 166 and converts theinput video signal into image data. This image data is supplied to theelectronic still-video camera 10 via the selectors 154 and 153, and theimage data is recorded in either the internal RAM 28 or external RAM 31,depending upon the setting of the memory selecting switch 13.

By changing over the operation selecting switch 136 to the position ofthe indicator mark 149, operation of the control panel 139 is enabledand operation of the electronic still-video camera 10 is disabled.

According to this embodiment, the recording circuit 157 is provided inthe electronic circuitry of the playback apparatus 110. However, it ispossible to eliminate the recording circuit 157 to obtain a playbackapparatus 180, of the kind shown in FIG. 6, which performs playbackprocessing only.

Third Embodiment

FIG. 7 illustrates the construction of a digital electronic still-videocamera according to a third embodiment of the present invention. Thoughit has not been stated explicitly in the first and second embodiments,the image data generally is subjected to data-compression processingbefore being stored in the external RAM of the memory cartridge or inthe internal RAM of the electronic still-video camera. The reason forthis is that the image data is highly voluminous and a large number offrames of image data cannot be stored in a semiconductor memory unlessthe data is compressed. When the image data that has been stored inthese memories is played back, the compressed image data is subjected toexpansion processing.

Image data generally is composed of luminance data Y and color data Cr,Cb. Each of these items of image data Y, Cr, Cb is subjected tocompression and expansion processing individually.

In this embodiment, a two-dimensional orthogonal transformation codingmethod is used to accomplish compression of the image data. Since thecompression processing regarding each of the items of image data Y, Crand Cb is the same (though naturally the values of the parameters usedin the compression processing differ), compression of only one type ofimage data, e.g., the luminance data Y, will be described.

The image data is divided into a plurality of blocks. For example, oneblock is composed of 8 dots×8 dots. The image data in each block issubjected to a two-dimensional orthogonal transformation (e.g., atwo-dimensional discrete cosine transformation, referred to as "DCT").The data that has been orthogonally transformed is normalized using apredetermined normalization coefficient (i.e., the data is divided usinga normalization coefficient), and data of a value smaller than thenormalization coefficient is discarded and made 0 (this is quantizationprocessing). The quantized data is then subjected to Huffman coding.

The processing for expanding the compressed image data is performedthrough a procedure which is the reverse of the foregoing. Specifically,first the compressed image data is decoded and then the decoded data issubjected to a two-dimensional orthogonal reverse transformation.Finally, the image data that has been expanded block by block iscombined (arrayed) in memory so as to construct one picture.

When a digital electronic still-video camera 200 shown in FIG. 7 is inthe recording mode, the image of a subject formed on a solid-stateelectronic image pick-up element such as a CCD through an imagingoptical system 201 is converted into an electric signal at the moment ashutter-release button (not shown) is pressed, and the electric signalis outputted by a CCD 202. The video signal representing the image ofthe subject outputted by the CCD 202 is subjected to pre-processing suchas amplification and white-balance adjustment in a preprocessing circuit203. The resulting signal is then converted into digital image data inan A/D converter circuit 204, and the digital image data is storedtemporarily in a frame memory 207 via a memory controller 205. In FIG.7, a circuit which controls the timing of read-out from the CCD 202 aswell as other operations is not shown.

The image data temporarily stored in the frame memory 207 is read out inthe order of sequential scanning under the control of the memorycontroller 205. The read image data is fed into aluminance-signal/color-signal (Y/C) processing circuit 206 following aframe/field conversion if this is necessary. Theluminance-signal/color-signal processing circuit 206 generates theluminance (Y) data and color (C=Cr+Cb) data from the inputted imagedata. These items of luminance data and color data are applied to theframe memory 207 to be stored there again.

Thereafter, the image data is read out of the frame memory 207 again andapplied to a DCT/reverse-DCT circuit 209. The latter compresses theimage data by the aforementioned DCT and expands the image data by theaforementioned reverse-DCT. As a result of the DCT conversion, theamount of data in one frame of image data is reduced, and therefore thenumber of frames capable of being recorded in an external memory 231 ofa memory card 230 or an internal memory 213 of the camera increases. Thecompressed image data is applied to the frame memory 207 to be storedthere again.

The compressed image data is read out of the frame memory 207 andapplied to the coding/decoding circuit 208. While the compressed imagedata is being coded by the coding/decoding circuit 208, it is directedthrough a card interface 211 and stored in the external memory 231 ofthe memory card 230 or the internal memory 213 of the electronicstill-video camera 200, depending upon the selection made by theselector 212. The selector 212 is controlled by a system controller 210.

As in the first and second embodiments described above, the electronicstill-video camera 200 has a connector 216 for connecting the memorycartridge 230 at will. When the memory cartridge 230 is connected viathe connector 216, the external memory 231 in the memory card 230 iscapable of being accessed by the system controller 210 of the electronicstill-video camera 200.

The digital electronic still-video camera 200 is equipped with theinternal memory 213. The internal memory 213 is constituted by asemiconductor memory, which is the external memory 231, and should havea storage capacity as large as practically possible. The internal memory213 can be a static RAM or, in order to obtain a high density and speed,a dynamic RAM. If a dynamic RAM is used, a refresh circuit 214 will berequired.

In the playback mode, an image having a designated frame number is readout of the external memory 231 or internal memory 213 from thecompressed image data stored in these memories. After being subjected toplayback processing, the read image data is either displayed in aviewfinder (constituted by a liquid-crystal display device, for example)218 or applied to an external display unit via a connector 217. Theconnector 217 is for connecting the external display unit.

More specifically, the compressed image data read out of the externalmemory 231 or the internal memory 213 is applied to the coding/decodingcircuit 208 via the selector 212 and interface 211, the data is decodedand the decoded data is stored in the frame memory 207. Thereafter, theimage data is read out of the frame memory 207 and applied to theDCT/reverse-DCT circuit 209, where the data is subjected to areverse-DCT. After the transformed image data is again temporarilystored in the frame memory 207, the transformed image data is read outof the frame memory 207 and applied to a playback processing circuit215. The playback processing circuit 215 converts the inputted digitalimage data into an analog video signal and outputs the signal uponconverting it into a signal suitable for displaying. The analog videosignal is applied to the viewfinder 218 to display the image, or isdirected through the connector 217 so as to be applied to an externaldisplay unit (not shown), where the image is displayed. With regard tothe output of the analog video signal, it goes without saying that achangeover switch can be provided for changing over between theconnector 217 and the viewfinder 218. Of course, the video signal may beapplied to both the connector 217 and viewfinder 218 simultaneously.

The system controller 210 executes control of the memory controller 205for compressing and expanding the image data in the manner describedabove; changeover control of the selector 212; control for changeoverbetween the recording and playback modes; control for accessing theinternal memory 213 and the external memory 231 and designating framenumbers; and control of display panel 221 and control panel 222,described below.

FIG. 8 illustrates an example of a display presented on the displaypanel 221. The display panel 221 is provided with a section 223 fordisplaying the selected mode, a section 224 for displaying informationrelating to the internal memory 213, a section 225 for displayinginformation relating to the external memory 231, and a section 226 fordisplaying the direction in which image data is transferred. Charactersindicating the selected mode are displayed in the section 223 (thecharacters for all available modes are shown in the drawing of FIG. 8).

FIG. 9 shows a portion of the control panel 222. The control panel 222is provided with a mode selecting button 233, a select button 234, asetting button 235, a shutter-release button 236, a DOWN button 237 forreverse feed, and an UP button 238 for forward feed. The electronicstill-video camera 200 has the following modes:

Recording Mode (REC)

In this mode, the subject is photographed and one frame of image dataobtained by such photography is recorded in the internal memory 213 orexternal memory 231.

Playback Mode (PB)

In this mode, one designated frame of image data stored in the internalmemory 213 or external memory 231 is played back.

Memory Change (or Memory Selection)Mode (CHANGE)

In this mode, it is decided whether recording or playback processing(inclusive of erasure) is to be performed with regard to the internalmemory 213 or external memory 231.

Copy Mode (COPY)

In this mode, one designated frame of image data is transferred betweenthe internal memory 213 and external memory 231 to be stored in eithermemory.

Copy-All Mode (COPY ALL)

In this mode, all of the stored image data is transferred between theinternal memory 213 and external memory 231 to be stored in eithermemory.

Erase Mode (ERASE)

In this mode, designated image data is erased from the internal memory213 or the external memory 231.

These modes can be selected by the mode selecting button 233. That is,each time the mode selecting button 233 is pressed, the mode beingdisplayed on the on the display panel 221 changes in a predeterminedorder. The mode that has been selected is that represented by thecharacters being displayed.

The operation in each of these modes will now be described.

When the recording mode (REC) is selected, the remaining number offrames that can be recorded in the internal memory 213 and the remainingnumber of frames that can be recorded in the external memory 231 aredisplayed in the display sections 224 and 225, respectively. Further,underline segments 224a or 225a in the display section 224 or 225corresponding to the memory (the internal memory 213 or external memory231) that has been set in the memory change (memory selection) mode(CHANGE) are lit. In the recording mode, after one frame of image datarepresenting the image of the subject photographed has been subjected tocompression processing, the compressed data is stored in whichever ofthe internal memory 213 or external memory 231 has been selected, as setforth above.

In the playback mode (PB), the frame number of the image being playedback is displayed in display section 224 or 225. The underline segment224a or 225a corresponding to the memory selected is lit. The framenumber of the image to be played back is incremented by pressing the UPbutton 238 and decremented by pressing the DOWN button 237. In theplayback mode, as set forth above, the image data having the designatedframe number is read from the internal memory 213 or external memory231, depending upon which has been selected, the read image data issubjected to expansion processing and playback processing, and theresulting data is then applied to the connector 217 or viewfinder 218.

If the memory change (selection)mode (CHANGE) has been selected,whichever of the underline segments 224a, 225a is lit in displayssections 224, and 225 is changed over each time the select button 234 ispressed. Lighting of the underline segment 224a indicates selection ofthe internal memory 213, and lighting of the underline segment 225aindicates selection of the external memory 231. When the setting button235 is pressed, selection of the memory corresponding to the currentlylit underline segment is finalized. The system controller 210 controlsthe selector 212 in accordance with the memory selection setting.

In the copy mode (COPY), the memory whose image data is to be read out(the originating memory from which data is to be transferred) is decidedby the memory change (CHANGE)mode. Of course, since the originatingmemory for the transfer and the memory which is the destination of thetransfer are set by setting the transfer direction, described below,this operation, along with the associated processing, is not necessarilyrequired. The frame number of the image data to be read out in theoriginating memory decided is designated by operating the UP button 238or DOWN button 237. The designated frame number is displayed in thedisplay section 224 or 225. By pressing the select button 234, whicheverof the two arrows in the display section 226 is lit is changed over. Thelower arrow pointing to the right indicates a transfer from the internalmemory 213 to the external memory 231, and the upper arrow pointing tothe left indicates a transfer from the external memory 231 to theinternal memory 213. When the shutter-release button 236 is pressed, thecopying operation is executed. Specifically, one frame of the image datahaving the designated frame number is read out of the selected memory213 or 231, this data is transferred to the other memory 231 or 213through the selector 212, and the transferred data is stored in a blankarea of the memory. It is permissible to adopt an arrangement in whichthe storage location or frame number of the image data in thedestination memory is designated. If it is arranged so that thistransfer is carried out while the image data to be transferred is beingdisplayed, the user will be capable of ascertaining which image data isbeing transferred.

In the copy-all mode (COPY ALL), the transfer direction is decided bypressing the select button 234, and the arrow indicating the directiondecided is displayed in the display section 226, just as describedabove. When the shutter-release button 236 is pressed, all of the imagedata stored in the originating memory is read out, and this data istransferred to and stored in the destination memory via the selector212.

In the erase mode (ERASE), the memory storing the image data to beerased is selected in the memory change (selection) mode, after whichthe frame number of the image data to be erased is designated using theUP button 238 or DOWN button 237. The image data having the designatedframe number is erased by pressing the shutter-release button 236.

In accordance with the electronic still-video camera according to thethird embodiment as described above, compressed image data indicative ofa photographic image can be preserved in the internal memory 213, andhence it is not always necessary to carry about a memory cartridge, justas in the case of the first embodiment. In addition, the image datapreserved in the internal memory 213 can be played back and displayedand, if necessary, the image data can be transferred to and stored inthe external memory of a memory cartridge.

Fourth Embodiment

FIG. 10 illustrates the construction of a digital electronic still-videocamera according to a fourth embodiment of the present invention.

An electronic still-video camera 240 according to the fourth embodimentdiffers from the electronic still-video camera 200 of the thirdembodiment shown in FIG. 7 in that the selector 212 and internal memory213 are not provided. The other components basically are the same asthose in the electronic still-video camera 200 of the third embodiment.

In FIG. 10, there is illustrated a switch 241 for detecting loading andejection of a memory card 230 (connection to and disconnection from theconnector 216). Though the memory-card detecting switch 241 is providedalso in the electronic still-video camera 200 of the third embodiment,it is not shown in the drawing of FIG. 7.

The memory-card detecting switch 241 can be realized by a switch whosecontacts are opened and closed by making contact with the loaded memorycard 230, or by processing executed by the system controller 210 inaccordance with a program. The latter alternative will now be describedin detail.

As illustrated in FIG. 12, the storage area of the external memory 231in the memory card 230 is divided into a header area and an image areawhich stores the image data. Recorded in the header area are a tuple ID(identification), which is an identification code indicating that thememory card is for a digital electronic still-video camera; a pointerindicating the data length of the tuple ID; a device ID indicating thespeed and type of the external memory 231; device-size data whichindicates the capacity of the external memory; and a tuple end code(generally FFh is used, in which h is indicative of a hexadecimalnumber) indicating the end of the tuple. The system controller 210addresses the area of the device ID in the header area of the memorycard 230 and reads the data stored in this area. If the memory card 230has been connected to the connector 216., the device ID is read. Thedevice ID generally is data other than OOh. Therefore, if the read datais other than OOh, the system controller 210 renders a decision to theeffect that the memory card 230 has been connected to the connector 216.Since the data bus has been pulled down to the L level, the read datawill be OOh as the memory card 230 has not been connected. In this case,the system controller 210 decides that the memory card 230 has not beenloaded.

In the digital electronic still-video camera 240 of the fourthembodiment, it is possible to photograph at least one more frame even ifthe image area of the external memory 231 in memory card 230 has beenfilled to capacity with image data and storage of any additional imagedata is impossible, or even if the memory card 230 has not been loaded.

Reference will be had to FIG. 11 to describe the processing which makesphotography possible even when the image area of the external memory 231in memory card 230 has been filled to capacity with image data. Thisprocessing is executed mainly by the system controller 210.

When the power supply is turned on at step 251 and the memory card 230is inserted (connected), this is sensed by the detecting switch 241 atstep 252.

If the memory card 230 has been connected to the connector 216, the datain the header area and in the other required areas of the externalmemory 231 is read, the capacity of the blank area of external memory231 or the number of already recorded frames is determined based uponthe read data, and the number of remaining frames capable of beingrecorded on the memory card 230 is obtained. The remaining number offrames is displayed on the display panel 221 (step 253).

Irrespective of whether the number of remaining frames is zero or someother number, depression of the shutter-release button is allowedunconditionally. If the shutter-release button is pressed, the imagedata obtained by photography is stored in the frame memory 207 at step254. Processing for producing luminance (Y) data and color (C) data fromthe image data obtained is executed by the Y/C processing circuit 206,and the luminance data and color data obtained as a result is stored inthe frame memory 207 again at step 255.

After this Y/C processing, it is determined at step 256 whether thenumber of remaining frames previously detected is zero, namely whethercompressed image data is no longer capable of being recorded on thememory card 230.

If the memory card 230 has a blank area in which recording is stillpossible, namely if the number of remaining frames is not zero,image-data compression processing by DCT and coding is executed at step257, and the compressed image data is recorded in the external memory231 of memory card 230 at step 258. The program then returns to step253.

In a case where the number of frames remaining in memory card 230 iszero, image data can no longer be recorded in the memory card 230.Accordingly, the display panel 221 displays a message calling for thememory card 230 to be exchanged for a new memory card, and an automaticpower turn-off operation is cancelled at step 259. The automatic powerturn-off operation refers to processing for turning off the main powersupply automatically if, after a picture is taken, a prescribed periodof time elapses without a picture being taken again. When the operatingpower ceases being supplied, the image data (Y, C data) that has beenpreserved in the frame memory 207 is erased.

When the user exchanges a full memory card for a new memory card or forone having a blank area in which at least one frame of image data can berecorded, ejection of the full memory card and loading of the new memorycard are detected by the detecting switch 241 at step 260.

Thereafter, if the system controller 210 accesses the external memory231 of the newly loaded memory card 230 and, at step 261, finds a blankarea in which image data is capable of being recorded, the luminancedata and color data preserved in the frame memory 207 is compressed at apredetermined compression ratio at step 257, after which the compresseddata is recorded on the new memory card at step 258. If the newly loadedmemory card 230 does not have a blank area, a message is displayed andprompts the user to exchange the memory card for another again. Thecompression ratio in the processing for compressing the image data maybe set automatically or manually by using the control panel 222.

In order to make photography possible even if no memory card has beenloaded, the program proceeds to step 253 for display of the remainingnumber of frames, step 254 for shutter release and step 255 for Y/Cprocessing even when a NO answer is received at step 252. The image dataresulting from Y/C processing is preserved in the frame memory 207. Ifthe memory card is not subsequently inserted, a message calling for cardinsertion is displayed and automatic power-off is cancelled, just as atstep 259. After insertion of the memory card has been sensed, theinserted memory card is searched for a blank area, in a similar manneras in steps 260 and 261. If a blank area exists, it will suffice tocompress the image data preserved in frame memory 207 and write thecompressed data in the memory card, in a similar manner as in steps 257and 258.

Thus, when it is desired to perform photography beyond the fixed numberof frames allowed by a memory card, at least one frame can be preservedtemporarily, irrespective of the compression ratio, by utilizing theframe memory which is an essential component in the digital signalprocessing executed within a digital electronic still-video camera.Further, even if no memory card has been inserted, the image dataresulting from photography can be preserved temporarily in the framememory. Then, when a new memory card is loaded in the camera, the cameraoperates in such a manner that the temporarily preserved image data isrecorded on this memory card. This makes the camera much more convenientfor the user.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

What is claimed is:
 1. An electronic still-video camera comprising:imagepick-up means for picking up an image of a subject and outputting avideo signal representing the image of the subject obtained; recordingsignal processing means for converting the video signal outputted bysaid image pick-up means into digital image data suited for storage in amemory device, and for compressing the digital image data; buffer memorymeans, used in the recording signal processing by said recording signalprocessing means, for temporarily storing the image data; an internalmemory for storing the compressed image data; a connector for loadingand unloading a memory cartridge at will, said memory cartridgeincorporating an external memory for storing the compressed image data;a shutter-release button; mode selecting means for selecting one ofrecording, copy and copy-all modes; memory selecting means for selectingone of the internal memory and the external memory; frame numberdesignating means for designating a frame number to be transferred;transfer direction designating means for designating one of a firsttransfer direction from the internal memory to the external memory and asecond transfer direction from the external memory to the internalmemory; transfer triggering means for instructing the start of transferof the image data; recording control means, in response to a signal fromsaid shutter-release button when the recording mode is selected by saidmode selecting means, for writing the compressed image data outputted bysaid recording signal processing means in the selected one of theinternal memory and the external memory selected by said memoryselecting means; first transfer means, in response to a signal from saidtransfer triggering means when the copy mode is selected by said modeselecting means, for transferring one frame of the compressed image datahaving the frame number designated by said frame number designatingmeans in the one of the first and second transfer directions designatedby said transfer direction designating means; and second transfer means,in response to a signal from said transfer triggering means when thecopy-all mode is selected by said mode selecting means, for transferringall compressed image data in the one of the first and second transferdirections designated by said transfer direction designating means. 2.An electronic still-video camera comprising:image pick-up means forpicking up an image of a subject and outputting a video signalrepresenting the image of the subject obtained; recording signalprocessing means for converting the video signal outputted by said imagepick-up means into digital image data suited for storage in a memorydevice; buffer memory means, used in the recording signal processing bysaid recording signal processing means, for temporarily storing theimage data; an internal memory for storing the image data; a connectorfor loading and unloading a memory cartridge at will, said memorycartridge incorporating an external memory for storing the image data; ashutter-release button; mode selecting means for selecting one of arecording mode and a copy mode; memory selecting means for selecting oneof the internal memory and the external memory; transfer directiondesignating means for designating one of a first transfer direction fromthe internal memory to the external memory and a second transferdirection from the external memory to the internal memory; transfertrigger means for instructing the start of transfer of the image data;recording control means, in response to a signal from saidshutter-release button when the recording mode is selected by said modeselecting means, for writing the image data outputted by said recordingsignal processing means in the selected one of the internal memory andthe external memory selected by said memory selecting means; andtransfer means, in response to a signal from said transfer trigger meanswhen the copy mode is selected by said mode selecting means, fortransferring at least one frame of the image data in the one of thefirst and second directions designated by said transfer directiondesignating means.
 3. The camera according to claim 2 wherein saidtransfer trigger means comprises said shutter-release button.